for an 8 inch sub. haven't decided on the sub yet. opinions? too long? the red is 1/2 inch instead of 3/4.
http://i88.photobucket.com/albums/k171/kcdc30/transmissionlinebox.jpg

da box king

01-14-2009, 09:18 PM

what driver?

azimuth

01-14-2009, 09:22 PM

what driver?

not sure yet. i need an 8 with a low .qts, qes and an fs close to 40.

RAM_Designs

01-14-2009, 09:41 PM

old assassin?

azimuth

01-14-2009, 09:42 PM

old assassin?
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=264-854
possibly. this tang band has a low .qes and .qts, but the fs is a little low. where can i find those?

azimuth

01-14-2009, 09:47 PM

RE 8's also have a low qts and qes, but fs is far under 40hz.

Rashaddd

01-14-2009, 10:12 PM

use corner pieces, and recalculate the length, it will be shorter

azimuth

01-14-2009, 10:24 PM

use corner pieces, and recalculate the length, it will be shorter

i might do that.

Rashaddd

01-14-2009, 10:29 PM

i might do that.

without them, you have significantly varying line areas which usually has adverse effects, such as killing output

and when you add them, you definitely need to recalculate the length because you'll lose a few inches or more in each of the corners

azimuth

01-14-2009, 10:32 PM

without them, you have significantly varying line areas which usually has adverse effects, such as killing output

and when you add them, you definitely need to recalculate the length because you'll lose a few inches or more in each of the corners

don't i calculate down the middle? i planned on putting in 45 degree wedges in the corners, but didn't know they shorten the actual length.

Pyro_By_Nature

01-14-2009, 11:01 PM

Looks ok, but why does it look like the sub is inverted in your drawing :confused:

FootlongSam

01-14-2009, 11:13 PM

I'm not sure about this design. I mean do it, and let us know how it sounds, but the t-lines that I've been playing around with (granted I just started ~8 months ago, and have only built a handfull of them) have always had a loading chamber, a compression chamber, an expansion chamber, and an acceleration chamber. T-lines can be picky, but when built properly they will slam. I'm interested to see how this turns out. I'm still in the begining stages of learning about t-lines, so any info on how this box performs is appreciated.

azimuth

01-14-2009, 11:15 PM

Looks ok, but why does it look like the sub is inverted in your drawing :confused:

it is inverted.

loud-n-low

01-14-2009, 11:17 PM

e8, crystal cmp?

azimuth

01-14-2009, 11:18 PM

I'm not sure about this design. I mean do it, and let us know how it sounds, but the t-lines that I've been playing around with (granted I just started ~8 months ago, and have only built a handfull of them) have always had a loading chamber, a compression chamber, an expansion chamber, and an acceleration chamber. T-lines can be picky, but when built properly they will slam. I'm interested to see how this turns out. I'm still in the begining stages of learning about t-lines, so any info on how this box performs is appreciated.

i don't even have as much experience as you. never done a t-line before. it's perfect for a false floor design in my s10. less than 10 inches high, spanning the entire floor surface of my extended cab.

Rashaddd

01-14-2009, 11:19 PM

don't i calculate down the middle? i planned on putting in 45 degree wedges in the corners, but didn't know they shorten the actual length.

I'll illustrate it for you in a sec

mokedaddy

01-14-2009, 11:23 PM

Oh jeese. Does everyone just through together a 1/4 wave and call it a t-line?

Rashaddd

01-14-2009, 11:26 PM

Alright in this example, port length goes from 30 inches down the middle, to 28.25 inches down the middle
http://img107.imageshack.us/img107/7583/cornershorterap5.jpg

the labelled parts are the parts we are concerned with as they change when the middle of the corner changes

azimuth

01-14-2009, 11:28 PM

Oh jeese. Does everyone just through together a 1/4 wave and call it a t-line?

that's why i posted it *******. never done one, so i started a discussion to learn more. what a tragedy. post something useful or avoid the thread.

azimuth

01-14-2009, 11:29 PM

Alright in this example, port length goes from 30 inches down the middle, to 28.25 inches down the middle
http://img107.imageshack.us/img107/7583/cornershorterap5.jpg

the labelled parts are the parts we are concerned with as they change when the middle of the corner changes

Here is a very good read by the man credited with the discovery of the t-line.

mokedaddy

01-14-2009, 11:58 PM

Fixed. Nice grammar Moke. You of all people.

Btw, are T-lines even popular in CA applications?

I just haven't heard much about em at all

Meh, it happens.

And honestly they really arent practical for most people in car audio due to high cabin gains, largeness of the enclosure, reflections... yada yada yada. I have seen and implemented quite a few with mixed success though. There are a lot of variables and you usually can get similar if not better results using a simpler design when all other things are considered.

Now give me a couple 18s in a large t-line for home audio, :drool:

azimuth

01-15-2009, 12:04 AM

Dont get your ******* in a wad, I wasnt talking to you.

It really should taper though as that will eliminate standing waves. Also what to you plan on using to dampen the sound waves inside the enclosure?

taper smaller or larger from the sub? i was just going to spray rubberized undercoating inside.

azimuth

01-15-2009, 12:06 AM

Meh, it happens.

And honestly they really arent practical for most people in car audio due to high cabin gains, largeness of the enclosure, reflections... yada yada yada. I have seen and implemented quite a few with mixed success though. There are a lot of variables and you usually can get similar if not better results using a simpler design when all other things are considered.

Now give me a couple 18s in a large t-line for home audio, :drool:

i read the same about them being impractical, but i want to try anyway.

mokedaddy

01-15-2009, 12:16 AM

taper smaller or larger from the sub? i was just going to spray rubberized undercoating inside.

I have a habit of going larger to smaller from sub to end of port, but as long as they arent exactly parallel it shouldnt matter. And I would definitely use some kind of acoustical stuffing at least one the walls.

i read the same about them being impractical, but i want to try anyway.

No harm in that. Like I said I have done quite a few over the years and even had one in my personal vehicle for a while.

ContourSPL

01-15-2009, 01:48 AM

I've had mixed reviews on TL's. I'v read people saying that they don't have as much output as a ported enclosure and vice versa. At the same time, I've seen TL's with a compression chamber do 150 on the Termalb at 20 hz with four 10's. But when does a TL with a compression chamber differ from a ported enclosure with an extremely long port? Hell, anybody can make a ported enclosure with the port length a quarter wavelength of 20 hz I know that dB's don't necessarily mean much but we are talking about subwoofers hear :) Since I'm an SPL guy at heart, I like loud, peaky bass. I think maybe an expanding transmission line would be cool since they have a bigger hump in the frequency response. It would be nice to be able for someone to do an actual comparison with a ported enclosure and a TL in the same vehicle with actual results.